2010 Tiguan Starting Gremlins

[anonymous-user]

so its a 2.0 tfsi and has about 27k miles. a few days back i turned the ignition after the car had been sat idle for a few hours following a drive. nothing happened. no clicking or anything else. the starter didnt turn and the only thing that happened was that the exclamation symbol stayed lit. car then fired up okay with a jumper. gave the battery an overnight charge and seemed fine for a few days until same problem again. jumped it again and then got a new battery. the old battery was showing about 11.8 across the poles with a domestic voltmeter. id normally think this was a sure sign that either the alternator or battery were borked.

car started fine first thing in the morning with the new battery. stopped after short 2m school run and then started fine again. stopped after school run number 2 and this time it wouldnt start. bear in mind that this is less than 16 hours after a new battery fully charged has been fitted.

dropped it off to local vw indy and he has checked the alternator, starter, new battery, checked for any drainage as well as fault codes on the ecu etc but nothing.

im really stuck as to what it could be. i do have an aftermarket parking sensor kit for the front which is activated by way of dash mounted toggle switch. could a fault with this circuit be the culprit? ive only been using the front pdc recently ie the switch has always been set to off previously. im wondering if this is the culprit?

i will ask the tech to check the chassis to engine earth strap again and i have read there is a ground screw on the fuel pump so will get that checked too.

its weird that it only happens once its been driven a but ie it tends to happen when the car is warm but even then not all the time.

any other thoughts??